This invention relates to the field of locks. More specifically, this invention relates to the field of U-locks with detachable crossbars which are commonly used for bicycles.
U-locks are commonly used for locking a bicycle to prevent theft of the bicycle. Ordinarily, a rider will lock the bicycle frame and at least one wheel to a post to secure the bicycle. Often, an experienced rider will remove the front wheel of the bicycle in order to lock it as well.
A U-lock principally includes a U-shaped shackle with two substantially straight and parallel arms coupled to one another by a curved bow, and a removable crossbar. In the prior art, the crossbar has been a bar or tube which includes two holes, each spaced about one inch from the opposite ends of the crossbar. A lock mechanism is fitted in the crossbar for securing the crossbar to the U-shaped shackle.
The U-shaped shackle is made of metal bar stock formed into a U-shape with the arms of the bar in the range of four to six inches apart. Typically, U-locks are designed to have two substantially straight parallel arms which are jointly locked within the crossbar, but may alternatively include a bent foot on one of the arms. The U-locks are locked by inserting the arms into the crossbar and activating the locking mechanism.
To lock a bicycle to a post or other object, the ends of the U-shaped shackle are passed around the post and a portion of the frame and/or one tire (or both) of a bicycle, and secured by the crossbar. It is impossible to predict the thickness of the post to which a rider may desire to lock a bicycle. Further, bicycles are available with a variety of sizes of frame tubes, frame tube spacing, tires and wheels. U-locks are also used to lock motorcycles, boats, jet skis and many other objects.